<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="bootstrap-3.4.1/css/bootstrap.css">
    <style>
        .box {
            width: 480px;
            min-height: 100px;
            margin: 100px auto 0 auto;
            border: 1px solid #dddddd;
            padding: 0 20px 20px 20px;
        }

        .box h2 {
            text-align: center;
        }
    </style>
</head>
<body>
<div class="box">
    <h2>用户登录</h2>

    <form>
        <div class="form-group">
            <label for="user">用户名</label>
            <input type="email" class="form-control" id="user" placeholder="请输入用户名">
        </div>
        <div class="form-group">
            <label for="pwd">密码</label>
            <input type="password" class="form-control" id="pwd" placeholder="请输入密码">
        </div>

        <button type="submit" class="btn btn-primary">登录</button>
    </form>
</div>
</body>
</html>